Generally, referring to FIG. 18, a first type of conventional waist twisting apparatus (60) comprises a first base (61), and a rotary post (62) is rotatably attached to a top portion of the first base (61). This kind of the waist twisting apparatus (60) can be stably placed on the ground, and the user can simply start the waist twisting movement by directly sitting on the rotary post (62). However, the waist twisting apparatus (60) mentioned above is disadvantageous because: (i) the waist twisting apparatus (60) does not match ergonomics when the user needs to sit down on the rotary post (62), and enters a position where the user's feet are off the ground and the legs are tucked into the body in an uncomfortable position before using the waist twisting apparatus (60); and (ii) the movement described in (i) may hamper the activities of a lower body of the user and the stretch of limbs, and reduce exercise effect. Furthermore, after a period of time, the user may get hurt.
Another type of conventional waist twisting apparatus (70), referring to FIG. 19, comprises a base (71), and four stabilizer beams (711) respectively protruding from a bottom portion of the base (71) is configured to stably support the base (71) on the ground. A crank (72) protruding from a top central portion of the base (71) is configured to connect to a cushion (73) which is adapted for a user to sit and achieve waist twisting exercise upon. However, this kind of the conventional waist twisting apparatus (70) is still unfavorable because: (i) although the stabilizer beams (711) are installed to support the base (71) of the waist twisting apparatus (70), the user still needs to sit in an uncomfortable way such as legs elevated; (ii) the crank (72) of the waist twisting apparatus (70) is exposed to the air, so that it is more likely to be contaminated or further blocked by foreign matters such as dusts; and (iii) Since the crank (72) is formed in a Z-shaped, the crank (72) is in an eccentric position of the base (71). In other word, the position of the cushion (73) is hanged above the base (71). Thus, the weight of the user pressing on the cushion (73) may cause larger frictions acting on a joint point between the crank (72) and the second base (71), further affecting the smoothness of rotation of the crank (72).
In light of each of two types mentioned above having its shortcomings, one of my previous inventions disclosed a waist twisting apparatus with a seat (80) in Taiwan Patent No. 201505586, referring to FIG. 20, comprising a base (81) and a crank (82). A lower end of the crank (82) is rotatably mounted on the base (81) while an upper end thereof is connected to a rotary post (83). Moreover, a seat (84) secured on a top portion of the rotary post (83) is configured for a user to sit upon.
However, the conventional waist twisting apparatus (80) is disadvantageous because: (i) the crank (82) is exposed to the air, so that it is more likely to be contaminated or further blocked by foreign matters such as dusts; (ii) the seat (84) further comprises a pair of handles (841) respectively formed at two lateral edge thereof. Although the handles (841) can provide a handhold for the user, it may reduce exercise effect of the waist of the user when the user exerts force on the handles (841). Furthermore, the users may tear their hand muscles accidentally during the twisting exercise; and (iii) this type of conventional waist twisting apparatus (80) has more components, including the base (81), the crank (82), the rotary post (83) and the seat (84), which increases the volume and the complexity of the waist twisting apparatus (80) and further raises the cost and the assembly difficulty of production. Therefore, there remains a need for a new and improved design for a waist twisting apparatus to overcome the problems presented above.